P21EE: Cylinder 10 Injector B Circuit Low

What does P21EE mean?

P21EE is the low-circuit code for the B injector of cylinder 10, the last cylinder of a V10. In practice that points to a ten-cylinder engine with two injectors per cylinder, of which only Lamborghini's Huracán is documented: its V10 pairs a direct injector with a port injector at each cylinder and was presented as the first V10 to combine both. Lamborghini does not publish which set is B or whether it uses this code. With cylinders 1 to 5 on one bank and 6 to 10 on the other, cylinder 10 is on the second bank. A short to ground is the core fault; CARB lets a maker report a broken wire under the same code instead of a separate open code. Before replacing parts, read the open code P21D8 and the A injector low code P0288 as well. High fault: P21EF.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Check engine light on
• Rough running or misfire on cylinder 10 (P0310)
• Fuel trim deviation on the second bank

Common causes

• High Cylinder 10 B injector wire grounded
• Medium Damaged or corroded injector connector on cylinder 10
• Medium Injector with internal ground fault
• Low Engine control unit output defective

Likelihood is a general estimate across vehicles; your make and model may differ.